Blister-Strip Inspection Device

ABSTRACT

The invention relates to a blister strip inspection device ( 10 ) for sensing blister segments ( 12 ) of a blister strip ( 14 ), having an image acquisition device ( 16 ) which is arranged to capture images of the blister strip ( 14 ), wherein the image acquisition device ( 16 ) comprises a digital camera ( 18.1 ), an advance sensing device ( 24 ) for continuously sensing an advance (x) of the blister strip ( 14 ), and an evaluating unit ( 40 ) which is connected to the digital camera ( 18.1 ) and to the advance sensing device ( 24 ), and which is configured to automatically perform a method having the following steps: (v) sensing the advance of the blister strip ( 14 ), (vi) determining a target time (t i ), at least also on the basis of the advance, at which a blister segment ( 12   .i ) is completely in the field of view ( 20.1 ) of the digital camera, and (vii) acquiring an image with the digital camera ( 18.1 ) at said target time (t i ), wherein the digital camera ( 18.1 ) is a video camera which has a field of view ( 20.1, 20.2 ) and is formed to capture an image sequence consisting of temporally successive images. According to the invention, it is envisaged that the evaluating unit ( 40 ) is configured to automatically (i) determine the target time (t i ) at which a blister segment ( 12   .i ) is completely in the field of view ( 20.1, 20.2 ), at least also on the basis of the advance (x), (ii) take an image (A i ) from the image sequence such that a monitoring image is generated, (iii) store the monitoring image and (v) repeat steps (i) to (iii) such that a monitoring image sequence is generated, and the evaluating unit ( 40 ) is configured to automatically: sense at least one preceding image at a time that lies shortly before the target time (t i ) and/or acquire at least one following image (A) at a time that lies shortly after the target time, determine which of the images sufficiently completely contains the greatest portion of a blister segment ( 12 ) by means of image recognition, and store said image (A) as a monitoring image.

The invention relates to a blister strip inspection device for sensingblister segments of a blister strip according to the preamble of Claim1.

So-called blister strips, which consist of a row of blister segments,are offered to patients to facilitate the intake of their medicaments.Each blister segment contains a compartment in which a medicament can bereceived. Moreover, the name of the patient, the contained medicamentsand a bar code for identifying the pouch are generally indicated on eachblister segment. Such blister strips are manufactured fully or partlyautomatically and are subject to strict quality control. For eachblister strip it is thus documented whether each blister segmentcontains precisely the right medicaments. Moreover, the content of eachblister segment of a blister strip is recorded and documented. This iscarried out by means of a blister strip inspection device.

A device for contactlessly recognising the location of wells for productis known from DE 102 49 962 A1, in the case of which it is sensed bymeans of image recognition if a required position of a well in a blisterstrip corresponds to the current position. If this is not the case, afeeding device is controlled such that it continues to correctly fillthe wells with the medicament. Such a device cannot be usedappropriately for blister strips without wells.

A device is known from U.S. Pat. No. 6,330,351 B1 which firstly sensesan identification number, then depicts the medicament which isassociated with this identification number on a screen, and alsocaptures and depicts an image of the blister pack so that a pharmacistcan compare if the medication specified according to the identificationnumber is indeed present in the pouch. Such a system does not allow anyautomated documentation regarding whether the correct medicaments werecontained.

A device for automatically sensing the contents of blister pouches,which works with light of different wavelengths, is known from WO2014/119994 A1. The contour of the contained medicaments is sensed bylight of one wavelength, the colour by another wavelength. From theinformation from each it is determined if these medicaments shouldindeed be a component of the blister pouch. Details regarding anydocumentation are not to be found.

A disadvantage of known blister strip inspection devices is that theyonly permit automatic documentation to a limited scope.

The underlying problem of the invention is to improve the documentationof the contents of blister strips.

The invention solves the problem by means of a blister strip inspectiondevice with the features from Claim 1.

Advantageously for such a blister strip inspection device, documentingthe contents of each blister segment is particularly easily possible.Via the advance sensing device it is thus possible to control the imageacquisition device such that it captures precisely one blister segmentin each image. A manual check, of whether the images captured by theblister strip inspection device indeed each only show one blistersegment and show this blister segment in its entirety, is therefore veryeasy. In the case of procedural steps, this leads to less complexity andallows a virtually fully automatic mode of operation.

In the context of the present description, a blister strip is inparticular understood to mean a longitudinally extended arrangement in arow of successive blister segments. Instead of referring to a blisterstrip, a tube blister can also be referred to. Instead of referring to ablister segment, a tube blister pouch can also be referred to. It ispossible but not necessary for a separation aid to be arranged betweentwo adjacent blister segments, for example a perforation. Preferably, atleast one medicament is contained in at least the greater part of theblister segments, in particular in all blister segments. In particular,at least the greater part of the blister segments, in particular eachblister segment, comprises a compartment for receiving medicaments, inparticular tablets and/or capsules.

Preferably, at least the greater part of the blister segments, inparticular each blister segment, has an identifier by means of which itcan be deduced what medicament is contained in the compartment. This canoccur by the link between the label and the medicament being filed in adata bank. The identifier preferably comprises a barcode and/or apattern code which could also be described as a 2D barcode.

The feature that the advance sensing device is formed to continuouslysense the advance is in particular understood to mean that the advancesensing device can detect a change in position of a maximum of onecentimetre, in particular of a maximum of 0.5 centimetres. This abilityto detect a change in position is independent of the position of theblister strip along its longitudinal extension.

An advance sensing device, which can only sense whether or not theblister strip has a label at a predetermined point, for example, is notformed to continually sense. In this case, it is possible to sense theposition of the blister strip with a high level of accuracy, but thisonly applies to the points of the blister strip which are directlyadjacent to the label. However, this is not a continuous sensing.

It is beneficial if the blister strip has at least two film layers. Inparticular, the blister strip is formed of a film tube which is laidflat. The two superimposed parts of the tube are preferably connectedsuch that the compartment for the medicament is formed. Naturally, it isalso possible that two films are otherwise connected to each other, forexample fused or adhesively bonded.

The advance sensing device has an optical advance sensing unit. Anoptical advance sensing unit is understood to mean a device whichautomatically determines the advance through a light signal. It is thuspossible, and represents a preferable embodiment, that the blister striphas recesses arranged at regular intervals, and the advance sensing unithas an interruption sensor for determining if there is a recess upstreamof the interruption sensor. The advance sensing unit is then formed toautomatically sense the number of recesses which have passed theinterruption sensor, and to calculate the advance from this number.

According to a preferred embodiment, the advance sensing device isformed to sense the advance by means of image correlation. In this case,the advance sensing device comprises a light source, for example alight-emitting diode or a laser, and an image sensor. The displacementof the pattern relative to the image sensor can be determined by meansof autocorrelation calculation between images which were capturedsuccessively. This principle is known from computer mice. Naturally, itis possible that the advance sensing device makes a determination bymeans of image correlation and also by means of mechanical contact inorder to determine the advance. It is possible, for example, that theadvance sensing device determines the respective one advance value bymeans of two or more methods, and then defines the advance from theadvance values, for example by means of averaging.

The image acquisition device comprises a digital camera and the blisterstrip inspection device has an evaluating unit which is connected to thedigital camera and the advance sensing device and is configured toautomatically perform a method with the steps of (i) sensing the advanceof the blister strip, (ii) determining a target time, at least also onthe basis of the advance, at which a blister segment is completely inthe field of view of the digital camera, and (iii) acquiring an imagewith the digital camera at this target time.

Determining the target time can be carried out, for example, by firstlysensing a start label. This can occur with an image acquisition device,for example, or with a sensor of the advance sensing device. It is alsopossible to manually set the start time or the location of the blisterstrip relative to the blister strip inspection device. As the length ofthe blister segments is known, the time at which a blister segment islocated precisely in the field of view of the digital camera can becalculated from the respective advance speed.

The feature that the blister segment is located completely in the fieldof view of the digital camera is understood to mean that such a greatscope of the blister segment is arranged in the field of view of thedigital camera that the elements of the blister segment which arecritical for the evaluation are recognisable. It is possible but notnecessary for the blister segment to be arranged entirely in the fieldof view of the digital camera.

The feature that determining the target time is carried out at leastalso on the basis of the advance is in particular understood to meanthat the advance is factored in when defining the target time. It ispossible but not necessary for further criteria to be taken into accountwhen defining the target time. However, if the advance cannot bedetermined, the time cannot be calculated either.

It is possible but not necessary for the target time to be directlydefined. It is thus possible for a trigger pulse to be generated, bymeans of which the image acquisition device is triggered and captures atleast one image. Alternatively or additionally, it is possible for atarget time to be expressed in a time unit. It is thus possible, forexample, for the evaluating unit to transmit a time at which an imageshould be captured to the image acquisition device. The imageacquisition device in this case features a clock and is configured totrigger at precisely this time.

It is beneficial if the image acquisition device comprises a videocamera which has a field of view and is formed to capture an imagesequence of temporally successive images, wherein the evaluating unit isconfigured to automatically determine the target time, at which ablister segment is completely in the field of view, at least also on thebasis of the advance, to take an image from the image sequence such thata monitoring image is generated, to store the monitoring image and torepeat said steps such that a monitoring image sequence is generated.

It is beneficial if this monitoring image sequence is linked to anidentifier of the blister strip. In this case, it can be ascertainedwhich medicaments are or were contained in the blister strip on thebasis of the monitoring image sequence.

The evaluating unit is configured to automatically perform a method withthe following steps: sensing at least one preceding image at the timethat lies shortly before the target time and/or sensing at least onefollowing image at a time that lies shortly after the target time, andto determine which of the images sufficiently completely contains thegreatest portion of a blister segment by means of image recognition, andto store said image as a monitoring image. If the advance sensing devicefor defining the advance had made a measuring error, this leads to nocomplete blister segment being recognised in the field of view, butinstead only a part of it. By contrast, at an earlier or later time agreater part of the blister segment would appear in the field of viewand thus in the image. By capturing a preceding image and/or a followingimage, it can be determined which image contains the greatest portion ofthe blister segment in the image. This image is more appropriate for themonitoring image than the image captured at the target time.

It is possible, and represents a preferred embodiment, that thecorrection to the previous blister segment is taken into account whendefining the target time for the next blister segment such that nocorrections are necessary when capturing the subsequent blister segment,provided that the advance sensing device has not made any measuringerrors.

The feature that the time lies shortly before the target time is inparticular intended to be understood to mean that a time differencebetween the target time and the time at which the preceding or followingimage is captured is less than a second, in particular less than 0.5seconds.

It is beneficial if the blister strip inspection device has a conveyingdevice for automatically conveying the blister strip. The conveyingdevice comprises a coiler and a decoiler, for example, wherein thesensing device is arranged such that it can capture between the coilerand the decoiler an image of the blister strip. It is possible but notnecessary for the advance sensing device or parts thereof to be acomponent of the conveying device. It is possible, for example, for theconveying device to convey the blister strip by means of a frictionalwheel and/or a mandrel and thus sense the advance. However, theconveying device is dispensable as it is possible to move the blisterstrip by manually pulling it through.

It is beneficial if the conveying device comprises a coiling devicewhich features a coiler and a drive motor for driving the coiler,wherein the drive motor is connected to the advance sensing device suchthat a rotational frequency of the coiler is dependent on the length ofthe blister strip which the advance sensing device has sensed. It isparticularly beneficial if the evaluating unit is connected to the drivemotor and is configured to control the drive motor. Since the coil onthe coiler continually widens when coiling the blister strip, therotational frequency with which the coiler must be rotated such that aconstant advance is achieved, decreases. In other words, the blisterstrip inspection device is configured to automatically calculate theradius of the coil on the coiler and to drive the drive motor of thecoiler such that the blister strip is movable with a constant advance.

It is also beneficial if the conveying device has a decoiler from whichthe blister strip is decoiled when the blister strip inspection deviceis in operation.

The method according to the invention is preferably performed by using ablister strip inspection device according to the invention.

The invention is explained more clearly hereinafter with the help of theenclosed drawings. In the drawings:

FIG. 1 shows a schematic view of a blister strip inspection deviceaccording to the invention and

FIG. 2 shows a blister segment as it is acquired at the target time byan image acquisition device of the blister strip inspection device.

FIG. 1 shows a blister strip inspection device 10 according to theinvention for sensing blister segments 12.1, 12.2, . . . of a blisterstrip 14. The blister strip inspection device 10 features an imageacquisition device 16 which, in the present case, comprises a firstcamera 18.1 and a second camera 18.2.

The first camera 18.1 features a first field of view 20.1, the secondcamera 18.2 features a second field of view 20.2. The blister stripinspection device 10 has a conveyor table 22 on which the blister strip14 is conveyed. The fields of view 20.1, 20.2 overlap on the conveyortable 22.

It can be recognised that the fields of view 20.1, 20.2 are formed suchthat their respective lengths L₁, L₂ on the conveyor table 22 correspondto at least one blister segment length L₁₄. It is therefore possible fora blister segment 12 to be captured by both cameras 18.1, 18.2 at thesame time.

The blister strip inspection device 10 features an advance sensingdevice 24 which, in the present case, has a frictional wheel 26. Thefrictional wheel 26 is arranged such that the blister strip 14, whichglides over the conveyor table 22, rotates the frictional wheel 26 in anon-slip manner. The frictional wheel 26 is connected to a rotationangle sensing device 28, by means of which a rotation angle φ is sensedas a function of the time t.

In the present case, the advance sensing device 24 is formed such thatit resolves an advance x, i.e. a movement on the conveyor table 22 alongan x-axis, with an accuracy of 0.1 millimetre. If the blister strip 14moves in the advance direction R, the advance x is continuously sensedby means of the advance sensing device 24. In other words, it is knownat any given time t, with an accuracy of at least one millimetre, in thepresent case 0.1 millimetre, how great the advance x is and thereforethe position of the blister strip 14 along the advance direction Racross the conveyor table 22.

In order to keep the slippage between the blister strip 14 and thefrictional wheel 26 as little as possible, the frictional wheel 26features a slip inhibiting element 30, in the present case in the formof a rubber tyre which is particularly preferably formed contoured. Thefrictional engagement between the frictional wheel 26 and the blisterstrip 14 is thus guaranteed.

The blister strip inspection device 10 can optionally feature apositioning sensor 32 which can recognise a schematically marked label34 of a blister segment 12 or of the blister strip 14. According to apreferred embodiment, it is envisaged, for example, that each blisterstrip 14 features at least one label on the basis of which the start ofa sequence of blister segments is recognisable. This label encodes, forexample, the start of a segment of the blister strip 14 which isintended for a particular patient. If this blister segment ends andanother blister segment follows for another different patient then theblister strip 14 features a further label.

However, it is also possible that each blister segment 12.i, i.e. theblister segments 12.1, 12.2, 12.3, . . . , has an individual label 34 onthe basis of which the contents of the blister segment can be defined. Acompartment 36.1 is thus schematically marked for the blister segment12.1 in which compartment a medicament 38.1 is contained. On the basisof the label 34.1, it can be ascertained by means of querying a databasewhich medicament 38.1 is contained in the compartment 36.1.

If a label 34 (reference numbers without number suffixes relate to allcorresponding objects) passes through the positioning transmitter 32,this thus senses the presence of the label. Since the locations of thelabels 34 are known for each blister segment 12, the position of theblister segment 12 on the conveyor table 22 is thus also known. Sinceeach location change of the blister strip 14 is determined by theadvance sensing device 24, the location of each individual blistersegment 12.i (I=1, 2, 3, . . . ) can be defined even if the positioningsensor 32 is not supplying an evaluable signal. This can be the case,for example, if the blister tube 14 is highly reflective.

The advance sensing device 24 is connected to an evaluating unit 40. Theevaluating unit 40 senses the advance x(t) of the blister strip 14 anddetermines at any given time t if a blister segment 12 is fully locatedin the field of view 20.1 and/or in the field of view 20.2. This is thecase for the blister segment 12.i at the target time t_(i). At thistarget time t_(i) the evaluating unit 40 triggers the cameras 18.1, 18.2such that they each capture at least one image.

FIG. 2 schematically shows an image A5 of the blister segment 12.5 whichis located in the fields of view 20.1, 20.2 of the cameras 18.1, 18.2 atthe target time t₅ The periphery of the image A5 is drawn with a plainline.

The label 34.5 which is formed by a barcode in the present case can berecognised. It can also be recognised that the blister segment 12.5 hasa written labelling 42.5 which is part of the label 34.5 and containsthe name of the patient and the time of intake at which the medicament38.5, in the present case the tablets 44 a, 44 b and 44 d, must betaken. The medicaments 38.5 are contained in the compartment 36.5.

The blister segment 12 is constructed of two film layers which arefirmly connected to each other and which consist of transparent plasticsuch that the medicaments 38.5 are visible.

FIG. 2 shows that two adjacent blister segments, in the present case theblister segments 12.5 and 12.4, are connected to each other via aperforation 46.5 such that they can be easily separated from each other.

The image A5 is sent from the camera 18.1 to the evaluating unit 40 andis stored there. The blister strip 14 moves continuously across theconveyor table 22. If the evaluating unit 40 calculates, based on thedata of the advance sensing device 24, that the following blistersegment, in the present case the blister segment 12.6, is located in thefield of view 20.1 of the first camera 18.1, a further image istriggered and is stored by the evaluating unit 40 such that it isunderstandable that immediately successive blister segments werecaptured. This results in an image sequence A1, A2, A3, . . . , which isstored in a tamper-proof manner in a memory of the evaluating unit suchthat to each blister strip 14 is unambiguously assigned the associatedimage sequence. The images which belong to the image sequence aredescribed as monitoring images.

If, as is illustrated in the present embodiment, two cameras (18.1,18.2) are present, each of the cameras takes at least one image, inparticular precisely one image such that two images are stored for eachblister segment.

It is possible that at least one of the cameras 18.1, 18.2 is a videocamera, which captures a continuous sequence of temporally equidistantimages which are cached. The evaluating unit 40 defines the times t_(i)at which a blister segment 12.i is located in the field of view of atleast one of the cameras and only takes the image from the stream ofimages in which the image of the blister segment can be recognised. Thedata volume which is to be stored is thus reduced.

In rare cases, it can occur that the advance sensing device 24 can causea measuring error. In that event, the respective blister segment 12 isnot centrally captured in the respective image A but is laterallydisplaced thereto. FIG. 2 shows the image A5 _(t−Δt) which was capturedat a time too early by Δt.

It can therefore be advantageous, without being necessary, that theevaluating unit 40 also takes at least one image from the stream ofimages of the at least one video camera which was captured at an earlieror later time, wherein the temporal interval Δt between temporallyadjacent images is preferably so small that the blister strip 14 hascovered a distance of at most 1 centimetre, for example at most 0.5centimetre in the corresponding time period.

The evaluating unit 40 then determines the location of the respectiveblister segment 12.i in the respective image A by means of a patternrecognition algorithm and selects the image in which the greatestpossible scope of the blister segment can be recognised. This can becarried out, for example, by means of the location of the label 34and/or the perforation 46 or another characteristic structure of theblister segment being determined and compared to a required position.The image for which this segment becomes minimal is selected and storedfor documentation. In the present example, this is the image A5 and notthe image A5 _(t−Δt).

The video camera thus captures, for example, the image sequenceA(t=t₀+nΔT), (n=1, 2, 3, . . . , ΔT being the temporal image interval),wherein the image A(t₀+n_(k)ΔT) in this notation corresponds to theimage A5 from above. The evaluating unit 40 then determines the locationof the label 34.5 in the images A(t₀+n_(k−1)ΔT)(=A5 _(t−Δt)),A(t₀+n_(k)ΔT) (=A5) and A (t₀+n_(k+1)ΔT) (=A5 _(t+Δt)), wherein (k=1, 2,3, . . . ) applies. Since the label 34.5 in the image A(t₀+n_(k)ΔT)(=A5) comes closest to the ideal location in the image, this image Ai=A5which was captured at the time t_(i)=₅=t₀+n_(k)ΔT is selected as amonitoring image and the remaining images of the blister segment 12.5are discarded.

In other words, as well as the image Ai (here: I=5) at least onepreceding image A5 _(t−Δt) is captured at a time t₀+n_(k−1)ΔT which liesby the image interval ΔT before the target time t5=t₀+n_(k)ΔT isacquired and a following image A5 _(t+Δt) is captured at a timet₀+n_(k+1)ΔT which lies by the image interval ΔT after the target time.It is then determined by means of image recognition which of the imagessufficiently completely contains the greatest portion of the blistersegment 12.i, and this image is stored as a monitoring image.

If it arises that the respective blister segment cannot be ideallyrecognised in the image, the spatial offset from the ideal position isdefined by the evaluating unit 40. In other words, the evaluating unit40 determines by which advance Δx the respective blister segment wouldhave to be displaced in order to be ideally situated in the respectivefield of view 20 of the camera. The time at which the next image istriggered is corrected by this correction such that systematic measuringerrors of the advance sensing device are corrected automatically.

The blister strip inspection device 10 comprises a conveying device 47for conveying the blister strip 14. The conveying device 47 comprises acoiling device 48 which has a coiler 50 and a schematically marked drivemotor 52 which in FIG. 1 is concealed by the coiler 50. When inoperation, the blister strip 14 is coiled on the coiling device 48. Theblister strip inspection device 10 also features a decoiling device 54which has a decoiler 56. It is possible but not necessary for thedecoiler 56 to be driven by a motor.

The drive motor 52 is connected to the evaluating unit 40. By means ofnumerical integration, the evaluating unit 40 calculates from theadvance x=x(t) the strip length L₁₄ of the blister strip 14 which isalready coiled on the coiler 50. A table or formula is left in thedigital memory of the evaluating unit 40, from which the rotationalfrequency is derivable, with which the drive motor 52 must be operatedsuch that the blister strip 14 is neither too tightly nor too looselycoiled on the coiler 50. Such a control of the rotational frequency is,however, dispensable.

Alternatively, for example, the drive motor 52 can be operated with aconstant torque which is selected such that the coil is coiled neithertoo tightly nor too loosely on the coiler 50. As an alternative to this,a device will also be present which senses how severely the blisterstrip 14 sags, and which controls the rotational frequency of the drivemotor 52 on the basis of the sagging of the blister strip.

It is possible that instead of from the decoiler 56 the blister strip 14is fed directly from a blister wrapping machine. Instead of a blisterstrip, a blister wrapping machine which comprises an inventive blisterstrip inspection device is also according to the invention.

List of reference numbers 10 Blister strip inspection device 12 Blistersegment 14 Blister strip 16 Image acquisition device 18.1 First camera18.2 Second camera 20.1 Field of view 20.2 Field of view 22 Conveyortable 24 Advance sensing device 26 Frictional wheel 28 Rotation anglesensing device 30 Slip inhibiting element 32 Positioning transmitter 34Label 36 Compartment 38 Medicament 40 Evaluating unit 42 Writtenlabelling 44a Tablet 46 Perforation 47 Conveying device 48 Coilingdevice 50 Coiler 52 Drive motor 54 Decoiling device 56 Decoiler A ImageL Length L₁₄ Strip length i Number index i = 1, 2, 3, . . . R Advancedirection t Time x Advance φ Rotation angle

1. A blister strip inspection device for sensing blister segments of ablister strip, comprising: (a) an image acquisition device arranged tocapture images of the blister strip, wherein the image acquisitiondevice comprises a digital camera, wherein the digital camera is a videocamera which has a field of view, and is formed to capture an imagesequence consisting of temporally successive images, (b) an advancesensing device for continuously sensing an advance of the blister strip,and (c) an evaluating unit which is connected to the digital camera andto the advance sensing device which is configured to automaticallyperform a method having the following steps: (i) sensing the advance ofthe blister strip, (ii) determining a target time, at least on the basisof the advance, at which a blister segment is completely in the field ofview of the digital camera, and (iii) acquiring an image with thedigital camera at the target time, wherein the evaluating unit isconfigured to automatically (i) determine the target time at which ablister segment is completely in the field of view, at least also on thebasis of the advance (x), (ii) take an image from the image sequencesuch that a monitoring image is generated, (iii) store the monitoringimage, and (iv) repeat steps (i) to (iii) such that a monitoring imagesequence is generated, and wherein the evaluating unit is configured toautomatically acquire at least one preceding image at a time which liesshortly before the target time and/or acquire at least one followingimage at a time that lies shortly after the target time, determine whichof the images sufficiently completely contains the greatest portion of ablister segment by image recognition, and store the determined image asthe monitoring image.
 2. The blister strip inspection device accordingto claim 1, wherein the advance sensing device is formed to sense theadvance by image correlation.
 3. The blister strip inspection deviceaccording to claim 1 further comprising a conveying device forautomatically conveying the blister strip.
 4. The blister stripinspection device according to claim 3, wherein the conveying devicecomprises a coiling device that includes a coiler and a drive motor fordriving the coiler, wherein the drive motor is connected to the advancesensing device such that a rotational frequency of the coiler isdependent on the length of the blister strip which the advance sensingdevice has sensed.